Biochemistry (Moscow), Vol. 66, No. 11, 2001, pp. 1300 1310. Translated from Biokhimiya, Vol. 66, No. 11, 2001, pp. 1609 1622. Original Russian Text Copyright © 2001 by Sineshchekov, Govorunova.
REVIEW
Rhodopsin Receptors of Phototaxis in Green Flagellate Algae O. A. Sineshchekov* and E. G. Govorunova
School of Biology, Lomonosov Moscow State University, Moscow, 119899 Russia; E mail: o.sineshchekov@mtu net.ru Received May 10, 2001 Revision received July 22, 2001
Abstract—Green flagellate algae are capable of the active adjustment of their swimming path according to the light direction (phototaxis). This direction is detected by a special photoreceptor apparatus consisting of the photoreceptor membrane and eyespot. Receptor photoexcitation in green flagellates triggers a cascade of rapid electrical events in the cell membrane which plays a crucial role in the signal transduction chain of phototaxis and the photophobic response. The photoreceptor current is the earliest so far detectable process in this cascade. Measurement of the photoreceptor current is at present the most suit able approach to investigation of the photoreceptor pigment in green flagellate algae, since a low receptor concentration in the cell makes application of optical and biochemical methods so far impossible. A set of physiological evidences shows that the phototaxis receptor in green flagellate algae is a unique rhodopsin